Thin Film Transistor Liquid Crystal Displays (TFT-LCDs) as a kind of flat panel display apparatus are more and more applied to the high-performance display field because they have traits of small volume, low power consumption, radiation-free, relatively low production cost, etc.
A TFT-LCD includes a color filter substrate and an array substrate disposed to be aligned with each other, with a liquid crystal layer provided therebetween. By means of controlling the deflection of liquid crystal molecules in the liquid crystal layer, control of light intensity is realized, so as to achieve an objective of displaying images.
Generally, the structure of an array substrate may be as shown in FIG. 1a, and it includes a plurality of gate lines 10 and data lines 11 that crisscross over each other. A plurality of pixel units 12 arranged in the form of a matrix are defined by the crossing of the gate lines 10 and the data lines 11, and a pixel electrode 104 is provided within each of the pixel units 12. The sectional view of the array substrate taken along the A-A′ direction is shown in FIG. 1b, and it includes multilayer thin film structures from bottom to top, such as, a gate electrode 101, a gate insulating layer 102, a semiconductor active layer 103, a pixel electrode 104, and a source/drain metal layer 105. For example, the above thin film structures may be fabricated in such a manner that a thin film layer and a photoresist are formed sequentially on a substrate, and then are subjected to masking, exposure, development, etching, stripping and other process.
However, during production and processing, due to the impact of external environment or production process, a thin film layer that should be etched away may be left over on the substrate. For example, the semiconductor active layer 103 or the pixel electrode 104 lying in a region between two adjacent pixel units 12 (in correspondence with a photoresist fully-removed region) should be fully etched away. However, during exposure and development, because a photoresist in the above photoresist fully-removed region is affected by the film-plating process of the former layer and its own process, the photoresist may not be fully exposed and a superfluous photoresist retained region is formed. On this basis, by a subsequent production process, it is possible that a residual portion (forming a conduction layer 20) of the pixel electrode 104 shown in FIG. 1c, or a residual portion (forming a conduction layer 20) of the semiconductor active layer 103 shown in FIG. 1d is formed between two adjacent pixel units 12. In this way, pixel electrodes 104 in two adjacent pixel units 12 are electrically connected, and when one of the pixel units 12 is controlled for display, a pixel unit 12 that is adjacent and electrically connected to it is lit up as well, resulting in occurrence of an uncontrolled bright pixel point (bright dot defect). This adversely affects the display effects and the product quality.
In order to solve the above problems, laser bonding or cutting process is generally adopted to repair a pixel point that suffers from a bright dot defect. For example, the array substrate is detected by an optical detection instrument, and when a bright dot defect is found, the above conduction layer 20 may be cut, so that two adjacent pixel units 12 are not electrically connected. However, because thickness of the pixel electrode 104 is relatively smaller, the degree of identification of the optical detection is reduced, and this leads to increasing of the miss probability of detection. And, when the above repairing process is carried out, other thin film structure that has already been formed, such as, a passivation layer, a common electrode layer or the like (not shown in the figure) located on a surface of the pixel electrode 104, may be damaged. Thus, repair effect of the bright dot defect is degraded, and quality of the product is affected.